Can any one correct my essay? I will take the Toefl exam eight days later.

subject:
Do you agree or disagree: childhood is the happiest time of a person's life

My essay:
Most people mentions their childhood as their happiest period of their life. I, myself, fully endorse that. I will employ one personal experience and a comprehensive evidence to support my idea.
To begin with, most of my funny memories are based on my childhood. Believe it or not, all friends of mine confirm that my childhood memories are the happiest story they have heard. Among them, a memory is so funny which my friends ask me to relate it for them again and again whenever we meet. Twenty years ago, when I was ten years old, my friends and I was watching the cars which passed by our alley. Suddenly, a black benz, benz is a car barnd, came in our view. I asked: "Mohamad! is this a benz?" Before Mohamad answering, Hasan, another friend of mine, answered loudly: "The benz is only white!" My childhood is full of such memories, and my childhood, personally, was my happiest period of my life.
Moreover, children do not have any burden to be angry about. I do not know any heavy burden which children experience except for light ones. Late Shari'ti, a prominent writer and philosopher in 20th-century Iran, has a fantastic motto: "I wish be a child, when my only problem was not to loss my pencil!" I tend to think the less burden you have, the happier you are. Considering this, I would be crystal clear which childhood is lack of big problem, hence is full of happiness.
In conclusion, from my point of view, childhood is the happiest period of lifetime. My childhood was full of funny memories that have made childhood so happy to me. In addition, I firmly believe that the less problem you have, the happier you are. And, childhood is the time in which every one has least problems.